Admittedly, the current earnings season is just beginning. But Fools with a bent for mining and commodities no doubt have noticed that a pair of metals companies have checked in with the sort of solid results that tend to enhance the notion that the world's economy continues on an upswing.

First up was Alcoa (NYSE: AA), which swung from a year-ago loss to solid earnings in its most recent quarter, handily beating analysts' estimates in the process. Next came Freeport-McMoRan Copper & Gold (NYSE: FCX) similarly checking in with strong results. Nevertheless, the company's share price was thumped Thursday by the combination of reduced forecasts for this year's copper and gold sales, along with concerns about the hot pace of China's economic expansion.

Freeport's net income for the quarter increased by fully 60% to $1.55 billion, or $3.25 per share, versus $971 million, or $2.15 a share, a year ago. The latest earnings easily topped the consensus expectation of $2.98 per share.

Also, on the positive side, while copper sales volumes of 941 million pounds were slightly below the 989 million pounds in the fourth quarter of 2009, the company benefited from an average price realization that increased 31% to $4.18, from $3.20 a year ago.

Gold sales volumes increased slightly, while the average price reached $1,398 per ounce, up from $1,115 last year. Molybdenum sales improved by a million pounds to 17 million pounds, while the price realizations for the element -- which is used in hardening steel -- increased to $16.60 per pound from $13.45.

Nevertheless, the harsh treatment of Freeport's shares on Thursday was due in part to slightly lower copper and gold sales volume guidance for 2011. The reduced expectations stemmed from planned mine sequencing to lower-grade ores at the company's massive Grasberg complex in Indonesia.

Also, portions of the market were affected by China's surprisingly strong economic growth, which caused concerns that the country's authorities could be compelled to adopt measures to tamp down inflation. Those concerns carry with them the notion that Chinese powers-that-be might overcorrect in the process.

We'll gain clarity regarding domestic and global economic expectations during the next few weeks when we receive earnings from the likes of U.S. Steel (NYSE: X) and Nucor (NYSE: NUE), along with mining giants BHP Billiton (NYSE: BHP) and Vale (NYSE: VALE), all of whose release dates are approaching. (As is a two-for-one split of Freeport's shares, effective February 1, 2011.)

In the meantime, copper prices have risen for two straight years and the climb shows no indication of abating. With output from some areas of the copper-producing world beginning to slacken, I continue to believe that, especially with its long-lived and geographically diverse assets, Freeport-McMoRan merits close attention.

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We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. Fool contributor David Lee Smith doesn't own shares in any of the companies named above. The Motley Fool has a disclosure policy.